I'm of the opposite opinion on that. I feel that the 1st season started out boring and that the series only truly picked up about half-way into the Dark Tournament arc. Also, the Chapter Black arc comes much later in the series, but its honestly what makes the series as great as it is, being that its probably my favorite anime arc out of any shounen series that I have ever seen.
As for the worst anime that I have ever seen, that's a pretty tough call to make, since I've seen quite a few ones which are so bad that they want to make me gag. However, as far as being the "ultimate worst" series, in terms of having bad animation, voice acting, music, story, characters, and everything, I'm not really sure what would fit the bill for me, since I'm not so sure that I've actually seen an anime that's bad in every single respect, but instead I have seen anime that may have been of average, or even good production quality, but which just had stories and/or characters that I just absolutely hated.